Send discontinuity at adjustments after shuffle/repeat mode changes.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=176749136

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java

@@ -476,8 +476,12 @@ import java.io.IOException;
       // position of the playing period to make sure none of the removed period is played.
       MediaPeriodId periodId = playingPeriodHolder.info.id;
       long newPositionUs = seekToPeriodPosition(periodId, playbackInfo.positionUs);
-      playbackInfo = playbackInfo.fromNewPosition(periodId, newPositionUs,
+      if (newPositionUs != playbackInfo.positionUs) {
+        playbackInfo = playbackInfo.fromNewPosition(periodId, newPositionUs,
           playbackInfo.contentPositionUs);
+        eventHandler.obtainMessage(MSG_POSITION_DISCONTINUITY, Player.DISCONTINUITY_REASON_INTERNAL,
+          0, playbackInfo).sendToTarget();
+      }
     }
   }